The basic function of any autopilot for marine vessels and the like is to establish a predetermined heading or course coupled with the capability of selectively modifying or deviating from a selected course. In more recent years, various types of electrical systems have been employed in association with a compass or other navigational aid to sense deviations from a selected course heading and to generate correction signals in order to return the vessel to the correct heading or course. Representative approaches are disclosed in U.S. Pat. Nos. 3,660,743 to W. Kundler et al; 3,665,281 to Y. Hirokawa; 3,670,227 to W. Kundler et al; 3,691,978 to D. S. Bond; 3,696,282 to Y. Hirokawa et al; 3,699,420 to W. Kundler et al; 3,741,474 to S. Kawada et al; 3,771,483 to D. S. Bond; 3,919,961 to J. A. McDougal; 3,927,635 to I. Masuzawa et al; 4,038,528 to J. T. Fowler; 4,074,648 to R. E. Reid et al; 4,103,638 to J. T. Fowler; and 4,129,087 to J. G. Dimmick et al. Characteristically, however, in such systems where a digital compass is employed to sense the actual course heading, the signals representative of course heading are transferred or transmitted as absolute numbers in a digital code which represents the actual bearing of the vessel. It is proposed to greatly simplify the method and means by which the steering of a vessel can be controlled. In this relation, it is desirable that both the amount of change and direction of a vessel can be sensed instantaneously with counteracting signals generated so as to return the vessel to its original heading. At the same time, it is desirable that the steering control permit selection of a new heading or course either to temporarily or permanently change course heading.